I did six infusions at 1.25mg/kg (because I have a high tolerance to.. Everything it seems?) and it lasted a few weeks~a month and a half. I did another batch of sessions 3 months later and the results were the same. I now take it as an intranasal spray at a much lower dose every other day. It makes me mentally exhausted for a few hours afterwards, but at least it provides me some ease on the mental burden I have. I've been in psychotherapy twice a week for nearly ten years, tried literally every drug aside from classic MAOIs and ECT. I've debated TMS/rTMS, but I'm concerned about the memory loss that I've read about and heard first hand accounts of from friends in similar situations.

Obviously everyone is different and YMMV, but for me- ketamine has been the only thing that made a real impact, bonus was the lack of nasty antidepressant side effects (I'm still taking an SSRI, SNRI, and a mood stabilizer and I hate them).

I'm hopeful that some of the new ketamine+___ compounds being created to extend the duration of the 'depression slightly lifted' feeling are successful and come to trial soon.